The invention relates to a space heating system with fuel cells and a connection to a public electrical network and a method for the operation of the system.
A space heating system is known from EP-A-1 205 993 in which thermal and electrical energy is recovered, and can be used, from a gas mixture containing hydrogen and carbon monoxide by means of high temperature fuel cells. A particular control is described with which a reliable and hazard-free operation of the system is ensured. The thermal energy can be used for heating service water and/or for space heating. The electrical energy can be used for the actuation of sensors and actuators (e.g. for the operation of pumps). A surplus of this form of energy can also be supplied to a public network. The gas mixture is led through a main gas valve arranged upstream of the fuel cells. The control of this valve is designed such that, on an interruption of the current required for the valve control, the valve closes and the energy-delivering operation of the fuel cells is thus stopped. An interruption over a longer period results in the fuel cells cooling. Interruptions to operation are damaging for the fuel cells because thermal cycles with cooling and renewed heating cause the electrochemically active components of the cells to age rapidly. Power interruptions in the public network therefore result in an ageing of the fuel cells which would not necessarily have to occur. With the aid of, for example, galvanic batteries or emergency power generators, the operation of the space heating system could be maintained if required when a network power cut occurs. Such support measures, however, mean added costs which only arise due to possible network power cuts; they also require a regular inspection and maintenance, e.g. recharging or replacing the batteries.